Ecophysiological adaptations of small mammals to the conditions of the cold climate [Adaptations écophysiologiques des petits mammifères aux conditions du climat froid].

Résumé

Already A.F. Middendorf (1869) indicated the most important adaptations of Siberian animals to cold: well-developed fur cover, ability to store fat reserves, adaptive behavior to the conditions of cold. In the 20th century schools of thought headed by physiologist A.D. Slonim and zoologists N.I. Kalabukhov and S.S. Schwartz contributed to the development of this problem. Our research on adaptation of animals was set in the Yakut State University and Institute of Biology Ya.B. SB USSR Academy of Sciences in the 60s-early 70s of the last century. The main objects of investigation are representatives of Sciuridae: Marmota camtschatica, Spermophilus undulatus, Spermophilus parryi and Tamias sibiricus; voles: Clethrionomus rutilus, Microtus gregalis, Microtus hyperboreus, Microtus oeconomus, synanthropic rodents: Ondatra zibethica, Mus musculus, Rattus norvegicus. Some interesting features, metabolism level and content of biologically active substances in tissues such as vitamin A and C were studied. A particular attention was given to the study of spatial and biological structure of populations, pattern of colonization over the territory, food and protective conditions, features of dynamics number. It has been determined that abundant species adapted to the conditions of the cold climate due to active metabolism, well developed chemical and behavioral thermoregulation, variability of morphophysiological parameters. The aboriginal forms adapt to cold at the expense of deeper physiological adaptations because of highly developed physical thermoregulation and strong seasonal metabolism changes. A disorder in the functioning of eco-geographical régulations according to Bergman and Allen causing a hypobiotic state has been observed in the forms most adapted to the cold. Very similar are the trends of physiological-biochemical variability during winter hibernation of small mammals and hypobiotic states in large mammals (Yakut horse, moose, reindeer).